The research appears to refute the claims of some sceptics that hypnosis is merely an exaggerated form of social compliance.

Crucially the work ñ conducted at the Weizmann Institute of Science at Rehovot in Israel ñ also offers fresh insights into how memory functions

Professor Yadin Dudai World-renowned neurobiologist Professor Yadin Dudai says brain scans of people taken after a hypnotic suggestion to forget have revealed how parts of the brain are affected.

The scans confirmed that hypnotic suggestions affected the neural circuitry of volunteers asked to forget and remember ñ akey to the memory suppression and recall process.

Professor Dudal and his team believe their insights into the memory suppression and recall process may yield insight into the mechanisms underlying amnesia.

During the study, two groups of volunteers ñ people susceptible to hypnotic suggestions, and individuals who were not ñ were shown a documentary depicting a day in the life of a young woman.

After a week, the participants were placed in a brain scanner. They were then induced into a hypnotic state, and given a posthypnotic suggestion to forget the movie, along with a reversibility cue that would restore the memory.

The researchers tested the subjects for their recall after they had come out of the hypnotic state. They then gave the participants the reversibility cue, and tested their recall again.

As compared to the hypnosis-non-susceptible group, the hypnosis-susceptible group showed reduced recall of the movie.

When the researchers analysed brain scans of the subjects, they found distinctive differences in specific brain areas ñ namely, occipital, temporal, and prefrontal areas - among participants in the two groups.

Professor Dudai, who currently holds the Sela Chair in Neurobiology and heads the Department of Neurobiology at the Weizmann Institute, commented: "The surprise for us was that activity was raised during memory suppression in one specific region in the frontal cortex,."

In effect, he added, it probably told the other brain regions "to don't even think about retrieving that memory".

"The one thing we can say for sure is that hypnotism worked under the conditions we used," said Prof Dudai, adding that the findings were different from those seen in people who attempted to deceive.

"We are therefore highly confident that this is not an artifact," he added.

The researchers believe that their insights into memory suppression and recall may help understand the mechanisms underlying some forms of amnesia, besides explaining how people suppress distressing memories or things.

The studyís co-author Avi Mendelsohn insisted however that further studies were needed to determine whether the new findings gave insights into how the brain stores memory.